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8262739: String inflation C2 intrinsic prevents insertion of anti-dependencies

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Reviewed-by: neliasso, chagedorn
This commit is contained in:
Tobias Hartmann 2021-03-29 12:40:11 +00:00
parent 19a6ac46ce
commit 3caea470e1
2 changed files with 65 additions and 0 deletions
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1
src/hotspot/share/adlc/formssel.cpp
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@ -781,6 +781,7 @@ bool InstructForm::captures_bottom_type(FormDict &globals) const {
!strcmp(_matrule->_rChild->_opType,"ShenandoahCompareAndExchangeP") ||
!strcmp(_matrule->_rChild->_opType,"ShenandoahCompareAndExchangeN") ||
#endif
!strcmp(_matrule->_rChild->_opType,"StrInflatedCopy") ||
!strcmp(_matrule->_rChild->_opType,"VectorMaskGen")||
!strcmp(_matrule->_rChild->_opType,"CompareAndExchangeP") ||
!strcmp(_matrule->_rChild->_opType,"CompareAndExchangeN"))) return true;

64
test/hotspot/jtreg/compiler/controldependency/TestAntiDependencyAfterStringInflation.java Normal file
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@ -0,0 +1,64 @@
/*
* Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/**
* @test
* @bug 8262739
* @summary Test correct insertion of anti-dependencies after String inflation.
* @run main/othervm -Xbatch
* compiler.controldependency.TestAntiDependencyAfterStringInflation
*/
package compiler.controldependency;
public class TestAntiDependencyAfterStringInflation {
static String reverseString(String str) {
int size = str.length();
char[] buffer = new char[size];
reverse(str, buffer, size);
return new String(buffer, 0, size);
}
static void reverse(String str, char[] buffer, int size) {
// Inflate String.value byte[] to char[]
str.getChars(0, size, buffer, 0);
// Reverse String by copying buffer elements. This will fail
// if C2 does not insert anti-dependencies between loads/stores.
int half = size / 2;
for (int l = 0, r = size - 1; l < half; l++, r--) {
char tmp = buffer[l];
buffer[l] = buffer[r];
buffer[r] = tmp;
}
}
public static void main(String[] args) throws Exception {
for (int i = 0; i < 50_000; i++) {
String res = reverseString("0123456789");
if (!res.equals("9876543210")) {
throw new RuntimeException("Unexpected result: " + res);
}
}
}
}